1. Field of the Invention
The present invention relates to a rail attachment structure where a rail member, such as a head box for a blind, is securely fixed to an attaching surface, such as the upper portion of a window frame.
2. Description of the Related Art
Conventionally, a head box for a blind is fixed on the upper portion of a window frame by a fixture, as disclosed in, for example, Japanese Unexamined Utility Model Publication No. 1-76995. The fixture includes a frame 31 and a slide block 32 as shown in FIG. 5. The slide block 32 is supported by the frame 31 to be slidable back and forth, and is urged forward by a spring 33. Hooks 34 are provided at the front end of the frame 31 to support the front upper edge of a head box 37. Hooks 35 are provided at the rear end of the slide block 32 to hold the rear upper edge of the head box 37.
To attach the head box 37 to the fixture, the front edge of the head box 37 is hooked on the hooks 34 of the frame 31.
The head box 37 is then pushed up, and the rear edge of the head box 37 touches the hooks 35 of the slide block 32 to move the slide block 32 backward against the force of the spring 33. The rear edge of the head box 37 then goes over the hooks 35 of the slide block 32 and is hooked on the hooks 35. At the same time, the hooks 35 are pressed against the rear edge of the head box 37, so that the head box 37 is securely fixed to the fixture.
The slide block 32 has a push bar 36 protruding forward over the frame 31. When the push bar 36 is pressed in, the hooks 35 of the slide block 32 are disengaged from the rear edge of the head box 37, allowing for removable of the head box 37.
In the conventional head box fixture as described above, however, the spring 33 should have a rather large urging force to securely hold the head box 37. This is because blind components, such as many slats, are hanging from the head box 37. When the head box 37 is to be attached, the urging force of the spring 33 becomes a load for a worker. Thus installation, requiring good strength. The spring 33 with a smaller urging force will cause the head box 37 to be insecurely held. The spring 33 therefore has to be designed to keep a balance between providing the force required for attachment and yet not having such a strong urging force so as to result in cumbersome operation.
In general, fixtures are provided in at least two locations in the lengthwise direction of the head box 37. Since greater operational force is required to attach the head box 37 to the fixtures at the same time, the head box 37 is therefore usually attached to the fixtures one after another. This is troublesome work. The work to remove the head box 37 is also tiresome, because the rear edge of the head box 37 has to be unhooked from the hooks 35 while keeping the push bar 36 pushed in the frame against the spring 33.